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The presence of secondary metabolites in Moringa oleifera is the decisive factor for the green synthesis of silver nanoparticles (AgNPs). Among the metabolites involved in this process, phenols and flavonoids in the plant extract are the two most important groups, acting both as reducing and stabilizing agents. M. oleifera, a well-known herb from Indonesia, was used in this study due to its exceptional properties, such as antioxidant, antimicrobial, and anti-inflammatory among others. The total phenolic content and total flavonoid content in the aqueous extract of M. oleifera leaves were determined, and the values were 62.01 ± 2.05 mg/g and 71.97 ± 0.94 mg/g, respectively. The synthesis factors including pH, extract volume, and temperature for the synthesis of AgNPs were optimized using the onefactor- at-a-time approach. The synthesis experiment showed that a pH of 8.0, an extract volume of 0.3 mL, and a temperature of 80°C resulted in the highest intensity of localized surface plasmon resonance at a wavelength of 419 nm, which favored the synthesis after 24 h of reaction time. Due to the remarkable content of metabolites, M. oleifera can be used as a promising candidate for the effective synthesis of AgNPs.

Microplastics have aroused global concern due to their widespread environmental distribution and the possible danger they pose to humans, animals, and microbes. In response to this concern, photocatalytic degradation, a technique that utilizes semiconductor nanomaterials as the photocatalyst, is being explored to reduce microplastics into less harmful compounds, making it a game-changing strategy for addressing this environmental problem. Besides the superiority of titanium dioxide (TiO2) as a photocatalyst, zinc oxide (ZnO) nanoparticles are also one of the semiconductors that have been widely explored to date. Studies have proven its potential to degrade microplastics in either solid- or aqueous phases. In the photocatalytic degradation of microplastics, the reactive oxygen species (ROS), including hydroxyl (•OH) and superoxide ions (O2•-), play an essential role in the process, resulting in the breakdown of the polymeric chain and the generation of reaction intermediates. Therein, the primary focus of this review is limited to the photocatalytic degradation of microplastics using a ZnO-based photocatalyst and its mechanisms. The exploration and comparison of microplastic's solid- and aqueous-phase photocatalytic processes in terms of their experimental setup and performance were also discussed further. Furthermore, an insight into future research prospects is also suggested here, based on the restrictions of present photocatalytic degradation systems. [ABSTRACT FROM AUTHOR]

Carboxymethyl cellulose (CMC)/polyvinyl alcohol (PVA)-Mn0.25Fe2,75O4/Ag ferrogels was fabricated by using the freezing-thawing method. Mn0.25Fe2.75O4/Ag magnetic fillers of ferrogels were synthesized by using coprecipitation and chemical reduction methods. Characterization of Mn0.25Fe2.75O4/Ag nanopowders was carried out using X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM), Vibrating Sample Magnetometer (VSM) instrument, and antimicrobial activity. At the same time, CMC/PVA-Mn0.25Fe2.75O4/Ag ferrogels were characterized by using magnetothermal instrument. The XRD pattern of the magnetite filler shows the peaks by the Fe3O4 and Ag phases, respectively. The TEM image, there are Mn0.25Fe2.75O4 and Ag with particle size distributions of 5–7 and 10–13 nm, respectively. The hysterical curve from VSM characterization shows a decrease in the value of magnetization saturation from 16.9 to 14.7 emu/g along with the addition of Ag material. Antimicrobial activity was tested using the agar diffusion method. Mn0.25Fe2.75O4/Ag samples showed very good results indicated by the widening of the zone of inhibition around the sample. Thus, CMC/PVA-Mn0.25Fe2.75O4/Ag ferrogels has the potential application to be applied in hyperthermia therapy as well as antimicrobial materials. [ABSTRACT FROM AUTHOR]

The novel severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) was responsible for the outbreak of coronavirus disease (COVID‐19). The respiratory illness has rapidly spread worldwide and has claimed millions of lives. Although most countries have entered the endemic phase, health authorities warned that future variants could be more virulent than the existing ones. Since clinical trials of antiviral drugs for COVID‐19 may last even a year before approval, developing alternative approaches to combat the virus becomes mandatory. Previously, carbon nanotubes (CNTs) have exhibited an impressive track record in controlling numerous viral diseases, including COVID‐19. In this article, we review recent applications of CNTs for the prevention, detection, and treatment of COVID‐19. We highlight the strategies and prospective developments of CNTs in producing personal protection equipment (PPE), vaccines, immune‐triggering, development of biosensors and therapeutic strategies. Finally, the challenges, limitations, and future outlook of CNTs in combating COVID‐19 are also discussed. [ABSTRACT FROM AUTHOR]

This study deals with the synthesis of zeolite from natural kaolinite using hydrothermal treatment and evaluation of its phase transformation behaviors. The synthesized zeolites were modified with silver ion by using the ion exchange method for the enhancement of antibacterial properties. The characterizations were performed by using X‐ray diffraction spectroscopy, Fourier‐transform infrared spectroscopy, field emission scanning electron microscopy, and energy‐dispersive X‐ray. Disk diffusion technique (DDT) was used for the evaluation of the antibacterial property of the modified zeolites. This study observed the transformation of kaolinite into amorphous metakaolin after calcination treatment at 900°C and the successful reconstruction of amorphous metakaolin into synthesized crystal zeolite in the presence of sodium hydroxide as an activating agent. It was also found that the zeolite type A was produced at 100°C, while sodalites were produced at 120 and 140°C. DDT analysis revealed that the modified zeolites showed significant antibacterial capability against Escherichia coli ATCC 11229 and Staphylococcus aureus ATCC 6538. In general, the present study has proven that the zeolites can be synthesized from natural material and can be modified with silver ion to enhance their antibacterial activity. [ABSTRACT FROM AUTHOR]

Adsorption capacity of pineapple leaf powder (PLP) and surfactant-modified pineapple leaf powder (SMPLP) in removing cationic dye, methylene blue (MB) and anionic dye, methyl orange (MO) from aqueous solution was investigated. SMPLP was prepared by reacting PLP with different concentrations of cationic surfactant, hexadecyltrimethylammonium bromide (HDTMA-Br). Batch mode experiments were conducted at room temperature to study the effects of initial dye and surfactant concentrations on the adsorption capacity of PLP and SMPLP towards cationic (MB) and anionic (MO) dye. The experimental adsorption isotherm data for both MB and MO fitted well with Langmuir in comparison to the Freundlich model. The maximum monolayer adsorption capacity for MB and MO were 52.6 and 47.6 mg/g, respectively. The highest adsorption for MB and MO were achieved by PLP and PLP treated with 4.0 mM HDTMA-Br, respectively. It was found that PLP and SMPLP showed different adsorption behaviour towards cationic and anionic dye. The MO adsorption was dramatically increased with PLP treated with 4.0 mM HDTMA-Br in comparison to PLP treated with 1.0 and 2.5 mM HDTMA-Br. Thus, the concentration of HDTMA-Br affects the adsorption capacity of SMPLP towards MO. The overall result implied that PLP can be applied as an effective adsorbent material to remove different types and classes of dyes from aqueous solution. [ABSTRACT FROM AUTHOR]

Chlorhexidine acetate-loaded silver-kaolinite (CA-Ag-Kaol) was prepared and characterised, and its application as an antibacterial agent was studied. CA-Ag-Kaol was prepared by the adsorption of chlorhexidine acetate (CA) (0.5 mmol/L) on Ag (50% of the Cation Exchange Capacity (CEC) of kaolinite) on kaolinite. Kaolinite (Kaol), silver-kaolinite (Ag-Kaol), CA-modified kaolinite (CA-Kaol) and CA-Ag-Kaol were characterised by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, field-emission scanning-electron microscopy (FESEM), energy dispersive X-ray (EDX) spectroscopy, zeta potential analysis and dispersion behavior measurements. The modification of kaolinite with cationic silver and chlorhexidine ions did not change the structure of kaolinite, and the characterization of the kaolinite samples revealed the successful loading of cationic silver and chlorhexidine ions on the kaolinite. The antibacterial assay of the samples was carried out against Escherichia coli ATCC 11229, Pseudomonas aeruginosa ATCC 15442, Staphylococcus aureus ATCC 6538 and Enterococcus faecalis ATCC 29212 using the disc diffusion technique (DDT) and the minimum inhibition concentration (MIC) technique. Based on the antibacterial assay, CA-Ag-Kaol showed better antibacterial activity than Ag-Kaol and CA-Kaol, and it performed well in both distilled water and a 0.9% saline solution. Gram-positive bacteria were more susceptible to the antibacterial behavior of Ca-Ag-Kaol than Gram-negative bacteria. In conclusion, silver-kaolinite that has been loaded with chlorhexidine acetate can be used as an effective antibacterial agent because of its high antibacterial activity against wide spectrum of bacteria in solutions containing electrolytes (saline solution). [ABSTRACT FROM AUTHOR]

The antibacterial activity of regenerated NaY zeolite (thermal treatment from cetyltrimethyl ammonium bromide (CTAB)-modified NaY zeolite and pretreatment with Na ions) loaded with silver ions were examined using the broth dilution minimum inhibitory concentration (MIC) method against Escherichia coli ( E. coli ATCC 11229) and Staphylococcus aureus ( S. aureus ATCC 6538). X-ray diffraction (XRD), attenuated total reflectance–Fourier transform infrared (ATR–FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX) and chemical elemental analyses were used to characterize the regenerated NaY and AgY zeolites. The XRD patterns indicated that the calcination and addition of silver ions on regenerated NaY zeolite did not affect the structure of the regenerated NaY zeolite as the characteristic peaks of the NaY zeolite were retained, and no new peaks were observed. The regenerated AgY zeolite showed good antibacterial activity against both bacteria strains in distilled water, and the antibacterial activity of the samples increased with increasing Ag loaded on the regenerated AgY zeolite; the regenerated AgY zeolite was more effective against E. coli than S. aureus . However, the antibacterial activity of the regenerated AgY was not effective in saline solution for both bacteria. The study showed that CTAB-modified NaY zeolite materials could be regenerated to NaY zeolite using thermal treatment (550 °C, 5 h) and this material has excellent performance as an antibacterial agent after silver ions loading. [ABSTRACT FROM AUTHOR]

Amine-functionalized, silver-exchanged zeolite NaY (ZSA) were prepared with three different concentrations of 3-aminopropyltriethoxysilane (APTES) (0.01, 0.20 and 0.40 M) and four different concentrations of silver ions (25%, 50%, 100% and 200% from zeolite cation exchange capacity (CEC)). The samples were characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray (EDX), surface area analysis, thermogravimetric analysis (TGA) and zeta potential (ZP) analysis. The FTIR results indicated that the zeolite was functionalized by APTES and that the intensity of the peaks corresponding to APTES increased as the concentration of APTES used was increased. The antibacterial activities of the silver-exchanged zeolite NaY (ZS) and ZSA were studied against Escherichia coli ATCC11229 and Staphylococcus aureus ATCC6538 using the disc diffusion technique (DDT) and minimum inhibitory concentration (MIC). The antibacterial activity of ZSA increased with the increase in APTES on ZS, and E. coli was more susceptible towards the sample compared to S. aureus. The FESEM micrographs of the bacteria after contact with the ZSA suggested different mechanisms of bacterial death for these two bacteria due to exposure to the studied sample. The functionalization of ZS with APTES improved the antibacterial activity of the silver-zeolite, depending on the concentration of silver ions and APTES used during modification. [ABSTRACT FROM AUTHOR]

Biosynthesis of silver nanoparticles (AgNP) using plant extracts is considered as an advanced method of synthesising AgNP using the green method. Although the leaf and the root of Ficus deltoidea Jack var. kunstleri (King) Corner (Mas Cotek) are known to have medicinal benefits, the study on its organs (leaf, stem, fig and root) to synthesise AgNP is still scarce. Therefore, this study determined the optimal synthesising conditions for AgNP-Leaf, AgNP-Stem, AgNP-Fig, and AgNP-Root, involving the volumes of plant extracts (1.0, 1.0, 0.8 and 3.0 mL), reaction times (30, 21, 33 and 21 h), reaction temperatures (60, 90, 100 and 90 °C), and solution pH (10, 12, 10 and 12). Thermogravimetric analysis (TGA) discovered that AgNP-Stem had the highest organic decomposition. All biosynthesised AgNPs exhibited spherical and crystal structures, with the particle sizes in the order of AgNP-Root (15.4 ± 3.4 nm) < AgNP-Stem (20.5 ± 2.4 nm) < AgNP-Fig (21.3 ± 4.2 nm) < AgNP-Leaf (22.9 ± 4.3 nm), as measured by transmission electron microscope (TEM). Meanwhile, in the disc diffusion technique (DDT) and minimum inhibitory/bactericidal concentration (MIC/MBC) analyses, AgNP-Root exhibited more significant antibacterial activity against Escherichia coli (ATCC 11229) and Staphylococcus aureus (ATCC 6538) bacteria compared to other organs. Visible damage was found on the bacterial wall of S. aureus treated with AgNP-Stem when observed using field emission scanning electron microscopy (FESEM). Hence, the phytochemical compounds found in the F. deltoidea organs significantly influenced the characteristics of AgNP and subsequently impacted the antibacterial activity. • Green synthesis of silver nanoparticles using plant organs of F. deltoidea. • Biosynthesised AgNP optimized with volume, pH time and temperature parameters. • Characterization of AgNP significantly effect on antibacterial activity. [ABSTRACT FROM AUTHOR]

This paper discusses the formation of cetylpyridinium bromide (CPB), a cationic surfactant quaternary ammonium compound (QAC), immobilized on kaolinite with different initial CPB concentrations ([CPB] i ) and their effect on the antibacterial activity against Escherichia coli . The CPB-immobilized kaolinites were characterized by a CHNS analyzer, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), zeta potential (ZP) analysis and the amount of CPB adsorbed on kaolinite. The antibacterial assay of the samples was studied through the disk diffusion technique (DDT) against E. coli as a model bacterium. The amount of CPB adsorbed on kaolinite did not affect the structure of the parent kaolinite but affected the overall charge of the kaolinite and eventually affected their antibacterial activity. CPB-immobilized kaolinite with [CPB] i above the critical micelle concentration (CMC) possessed antibacterial activity because of reversal of the charge from negative to positive on the kaolinite surfaces, as proven by ZP analysis, which could allow the action of CPB molecules against bacteria cells. This was due to the bilayer formation of surfactant molecules via hydrophobic bonding of their long hydrocarbon chains on the kaolinite surfaces at surfactant concentrations above the CMC value. Therefore, one of the important factors in producing antibacterial agents from surfactant immobilized kaolinite (organo-clay) is by loading excess surfactant on the clay above its CMC level to ensure bilayer formation of surfactant molecules on clay surfaces. [ABSTRACT FROM AUTHOR]

Abstract: Quaternary ammonium compound (QAC)-zeolites A, X and Y were prepared and characterized and their antibacterial activity was studied against Bacillus subtilis. The presence of QAC molecules on the zeolites has been proven by Infrared (IR) Spectroscopy. The antibacterial activity of these materials was determined by Minimum Inhibition Concentration (MIC) technique. From MIC values, QAC-zeolite X has highest antibacterial activity than that of zeolites A and Y due to the higher amount of QAC adsorbed onto zeolites X. To sum up, zeolite X was found to be a good support system for antimicrobial agents of QAC against B. subtilis. [Copyright &y& Elsevier]

Zeolites P in sodium (NaP) and potassium (KP) forms were used as adsorbents for the removal of calcium (Ca2+) and zinc (Zn2+) cations from aqueous solutions. Zeolite KP was prepared by ion exchange of K+ with Na+ which neutralizes the negative charge of the zeolite P framework structure. The ion exchange capacity of K+ on zeolite NaP was determined through the Freundlich isotherm equilibrium study. Characterization of zeolite KP was determined using infrared spectroscopy and X-ray diffraction (XRD) techniques. From the characterization, the structure of zeolite KP was found to remain stable after the ion exchange process. Zeolites KP and NaP were used for the removal of Ca and Zn from solution. The amount of Ca2+ and Zn2+ in aqueous solution before and after the adsorption by zeolites was analysed using the flame atomic absorption spectroscopy method. The removal of Ca2+ and Zn2+ followed the Freundlich isotherm rather than the Langmuir isotherm model. This result also revealed that zeolite KP adsorbs Ca2+ and Zn2+ more than zeolite NaP and proved that modification of zeolite NaP with potassium leads to an increase in the adsorption efficiency of the zeolite. Therefore, the zeolites NaP and KP can be used for water softening (Ca removal) and reducing water pollution/toxicity (Zn removal). [ABSTRACT FROM AUTHOR]

The synthesized zeolite NaY from rice husk ash (RHA) and the commercial zeolite NaY both modified with surfactants in amounts equal to 50%, 100% and 200% of their external cation exchange capacity (ECEC) were used to remove chromate and arsenate anions from aqueous solutions. While the unmodified zeolite Y had little or no affinity for the Cr(VI) and As(V) anionic species, the surfactant-modified zeolite Y (SMZY) showed significant ability to remove of these anions from the aqueous solutions. The highest chromates and arsenates adsorption efficiency was observed from solutions of pH values 3 and 8, respectively because of the dominance of the univalent species of both anions. The adsorption equilibrium data were best fitted with the Langmuir isotherm model with the highest removal capacities observed for the SMZY initially prepared considering the hexadecyltrimethyl ammonium (HDTMA) amount equal to the 100% of the ECEC of zeolite Y. Synthesized SMZY remove Cr(VI) and As(V) more than the corresponding commercial one due to its lower silica to alumina ratio. Thus, the HDTMA-covered modified zeolite Y synthesized using RHA can be used to remove Cr(VI) and As(V) from water. [Copyright &y& Elsevier]

Forward osmosis (FO) has been recognized as the preferred alternative membrane-based separation technology for conventional water treatment technologies due to its high energy efficiency and promising separation performances. FO has been widely explored in the fields of wastewater treatment, desalination, food industry and bio-products, and energy generation. The substrate of the typically used FO thin film composite membranes serves as a support for selective layer formation and can significantly affect the structural and physicochemical properties of the resultant selective layer. This signifies the importance of substrate exploration to fine-tune proper fabrication and modification in obtaining optimized substrate structure with regards to thickness, tortuosity, and porosity on the two sides. The ultimate goal of substrate modification is to obtain a thin and highly selective membrane with enhanced hydrophilicity, antifouling propensity, as well as long duration stability. This review focuses on the various strategies used for FO membrane substrate fabrication and modification. An overview of FO membranes is first presented. The extant strategies applied in FO membrane substrate fabrications and modifications in addition to efforts made to mitigate membrane fouling are extensively reviewed. Lastly, the future perspective regarding the strategies on different FO substrate layers in water treatment are highlighted. [ABSTRACT FROM AUTHOR]

Excessive nitrate discharge into aquatic environment is a serious concern as it gives huge impacts on aquatic life as well as corrupts ecosystem and water sources. The effective treatment of nitrate-containing wastewater is essential for the sake of health and environmental protection. In this study, the adsorption of nitrate was carried out using porous rice husk silica functionalized with branched polyethyleneimine (RSi-bPEI). A series of experiments were conducted to measure several adsorption conditions, adsorption isotherms, kinetics, selectivity and reusability. Experimental results demonstrated that the functionalization with branched PEI (bPEI) has significantly improved the adsorption about 40% higher. The ideal conditions for the nitrate adsorption onto RSi-bPEI is at pH = 4, 0.5 g L−1 dose, 50 mg L−1 concentration and about 120 min adsorption time. The pseudo-second-order and Langmuir equations were the most suitable models to describe the nitrate sorption from aqueous solution with high correlation coefficient (0.99). The monolayer adsorption capacity was found to be 94.49 mg g−1 for RSi-bPEI and 47.46 mg g-1 for RSi. The reusability test manifested RSi-bPEI has good regeneration capacity, hence can be an ideal adsorbent for practical wastewater treatment. [ABSTRACT FROM AUTHOR]

Eggshell membrane (ESM) is a highly-collagenized, biopolymeric fibrous network generally considered domestic and industrial waste. However, its inherent extraordinary properties have made ESM widely used in different fields due to its high potential applications, especially in the biomedical field. In this study , a poly (Ɛ-caprolactone) (PCL) integrated ESM (PCL/ESM) nanofibrous mat is fabricated using an electrospinning technique to produce wound dressing materials with enhanced biocompatibility and antibacterial efficacy for potent tissue regeneration. The physicochemical, biological, and mechanical properties of the electrospun fabricated nanofibrous mat PCL (15% w/v) and PCL/ESM (0.5% w/v, 1.5% w/v, and 2.5% w/v) were investigated using FE-SEM, ATR-FTIR, DSC, and XRD. In addition, the water uptake ability, degradability, cell viability, and antibacterial activity of the mats were evaluated. The FTIR results revealed that the molecular interactions of ESM with the PCL are through hydrogen bond formation. The morphology and the nanofiber dimension of the electrospun fabricated mat are within the collagen dimensions present in the extracellular matrix. The overall results confirm that the PCL/ESM (2.5% w/v) have shown the most excellent mechanical properties with high biocompatibility and efficient antibacterial activity among the other fabricated mat. Therefore, this study suggests that electrospun PCL/ESM mat could be a potential material for wound dressing. • Eggshell membrane-loaded poly(ɛ -caprolactone) (PCL/ESM) mat is fabricated. • PCL/ESM mat shows great biocompatibility with good mechanical strength. • Electrospun PCL/ESM (2.5% w/v) mat exhibits excellent antibacterial activity. • Electrospun PCL/ESM mat might be a good wound-dressing material. [ABSTRACT FROM AUTHOR]